Resistance unit



Nov. 19, 1935. J, J, MUCHER 2,021,802

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Patented Nov. 19, 1935 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to resistance units, and has for an object to provide an improved construction whereiri the parts are so constructed and arranged that there is no danger of breaking any of the resistance elements during the assembling of the device, the invention being an improvement over `my co-pending application Serial No. 690,730, led September 23, 1933, which issued as Patent 1,982,475, November 27, 1934.

Another object of the invention is to provide an improved construction wherein a continuous resistance element may be presented formed of wire or other material and any desired number of contacts taken therefrom, without endangering the proper functioning of the resistance element.

A still further object of the present invention is to provide a resistance unit wherein there is provided a terminal base with a number of terminal members, one or more independent resistant elements, insulating sheathing members, and a protecting and clamping metallic sheathing.

An additional object, more specically, is to provide in a resistance unit a construction whereby the parts of the unit may be readily assembled without injuring any of the assembled elements.

In the accompanying drawing- Figure 1 is a top plan view of a resistance unit disclosing an embodiment of the invention;

Figure 2 is a longitudinal, vertical. sectional view through Figure 1 on the line 2 2;

Figure 3 is a transverse sectional view through Figure 1 on the line 3 3; Figure 4 is an'inverted perspective view of the metal sheathing showing part of the walls unfolded and ready to receive certain of the other parts:

Figure 5 is a perspective view of the terminal base shown in section in- Figure 2; Y

Figure 6 is a plan view of an insulating element adapted to insulate certain parts;

Figure 7 is a plan view on a reduced 'scale of the resistance element shown in Figure 2;

Figure 8 is a bottom plan view of a terminal base similar'to that shown in Figure 5, but made appreciably longer; y

Figure 9 is a plan view o1' a pair of resistance elements adapted to be used in connection'with the terminal bas'e shown in Figure 8;

Figure 10 is a perspective view similar to Figure 5 but showing a slightly modified structure.

Referring to the accompanying drawing by numerals, I indicates a metal sheathing or cas- "ingwhich is provided with a top 2 bent to form 'side walls 3 and I, said side walls being shown as upstanding in Fig. 4. When the device is completed, however, these walls are bent to form bottom plates 5 and 6, which plates are iiush with the end tabs 'I and 9said end tabs being formed from the respective end extensions 9 and 5 I0 projecting from the top 2.

In forming the metal casing or sheathing I slots or openings II, I2 and I3 are provided, as well as openings I4 and I5. Openings I4 and I5 are adapted to receive screws and other means 10 for clamping the resistance unit in position when in use, as illustrated in Fig. 2. The openings II to I3, inclusive, are intended to accommodate the respective terminals I 6, I1 and I8. The openings just mentioned are suiliciently large to permit 15 these terminals to project through ywithout contacting with the casing I, the insulating sheathing I9 acting to holdthe parts separated. As shown in Fig. 6 the sheathing I9 is provided with apertures 29, 2l and 22 to accommodate the vari- 20 ous terminals, said apertures being of a size to permit the terminals to have a rather tight sliding t whereby the terminals are spaced from the casing I, as illustrated particularly in Fig. 1.

It will be noted that the sheathing lIII has a section 23 which acts as a top, end tabs 24 and 25 which cover the ends 9 and I 0, and flaps 26 and 21 which wrap around the resistance unit 28 and the terminal base 29 when the parts are in proper operative position.

It will be noted that the various terminals I6, I1 and I9 are permanently connected to the terminal base 29, which base is preferably made from iiber or other desired insulating material which is comparatively strong but rather thin. As 35 shown in Fig. 5the terminal I1 extends through a suitable opening 30 in the base 29. 'I'he terminal I1 mergesinto a transverse strip which is shown in" Fig. '8, and which is bent around base 29 and forms clinching hooks or extensions 32 40 and 33. The endv terminals I6 and I9 extend across the end of the base 29 but are otherwise identical with terminal II and associated parts, whereby there are provided proper contact plates 34 and 35 merging into the terminals I6 and I8. 45

It will be understood that the constructions shown in Figs. 5 and 8 are identical except that the base 29 in Fig. 8 is made longer than the base 25 in Hg. 5. This arrangement of lengthening the base is to take care of the end-to-end resist- 5o ance elements 35 and 31, which elements may contact or may be spaced apart as long as the winding thereon engages the ilange or contact plate 3l.

It will be understoodlthat the resistance ele- CII ment may be provided with two parts, as shown in Fig, 9, or a greater number of parts, and the same idea carried out without departing from the spirit of the invention. In comparatively small resistance units a single unit, for instance, unit 28, is utilized, the same extending froml the terminal I6 to terminal IB, illustrated in Fig. 2. Where the resistance unit is longer, one or more additional elements may be used but at a point where the various resistance units are arranged end to end there must be a iiange or plate similar to plate 3l to contact with the wires of each resistance unit.

It is understood that in resistance units of the kind disclosed. the wire on the ber, bakelite or other plates 30 is very ne as, for instance, the diameter of a very thin hair. 'I'his wire is laid on the .unit base 38 by machinery and the wires are very close together and very fine. When the terminals are being applied to this ilne wire in any desired way, as for instance, in the way shown in my co-pending application above mentioned, it has been found that quite often a sharp corner or edge terminal will break one or more of the wires of the resistance element, and, consequently, when the unit is completed and tested it will be found to have an open circuit between certain terminals. Great diiiiculty has been experienced in securing by soldering, clamping or otherwise mounting a terminal for electrical engagement with fine wires just mentioned. These diftcultieshave resulted in much loss, as it is not known that there is an open circuit until after the unit is completed. By providing the terminal base 29, as shown in Fig. 5, along the terminals thereof, these dii'iiculties have been overcome and regardless of how ne the wire is, the completed unit almost invariably presents one hundred percent test.

When assembling the unit as shown in Figs. 1 and 2, the shell is formed until it appears as shown in Fig. 4. 'I'he insulating sheathing I! is then taken and placed in the casing so that the various apertures 2t to 22 will register with the corresponding openings Il to I3, inclusive, of the casing. The structure shown in Fig. 5 is then taken and the terminals inserted through the slots 20 to 22, and also through the openings II to I3, until the base 2! is pressing against the top section 23 o! sheathing I9. The resistance element 28 is then placed in position on top of the terminal unit 29, all the parts being inverted during the assembly. Aiter the element 2l has been placed in lposition, the ends 2l and 25 are bent to the desired position, and the naps 2i and 2l swung over to the position shown in Fig. 3. The device isl then placed in a machine and the parts 5 and 6 bent to their finished position as illustrated in Fig. 3, said bending causing the parts to be rmly clamped together. The clamping action naturally acts against the insulating sheathing I l, which may be asbestos or other desired insulation more or less resilient. This will cause the pressure on the parts 5 and l to make the resistance element 2l to be in a certain sense resiliently pressed against the anges or contact plates Il, Il and 25. In this way a good contact is formed with a number of turns of wire of the resistance element, without any sharp corners or edges engaging the winding.

In Fig. 10 a slightly diierent structure is shown to that illustrated in Fig. 5. As illustrated in this gure the base 3l is of insulating material and is cut the proper length but not provided with any apertures. The various terminals l0, 4| and 4I are each provided with a base flange l2 which is turned over the respective edges ot the base 3l and pinched at the under surface so as to present clamping spurs or ilanges I3 and M. By

clamping the base ange 42 as just described 5 the end terminals may be properly mounted and one or more intermediate terminals readily clamped in place at a desired point or points without the necessity of accurately providing a punched hole. As shown in Fig. 5 the distance 10 between terminals I1 and Il is shorter than between IG and Il. If it should be desired to provide a device of this kind with terminals equally spaced it would be necessary to make a new die so as to punch the hole centrally ot the base. In 15 the structure shown in Fig. 10 if the intermediate terminal was to be positioned centrally it would not be necessary to provide a new die but merelyto position the terminal centrally and then clamp the same in place. Also, if a special order should zo be received for two or more intermediate terminals there would be no diiiiculty as the additional terminals could be quickly and easily clamped at the respective points on the base Il.

I claimz- 25 1. A resistance unit comprising a rectangular metallic casing formed with a plurality oi apertures arranged in a straight line in one face, an insulating enclosure member arranged within the casing and provided with apertures registering with the apertures in the casing, a terminal base fitting -fiatwise against said insulation, a pair of end terminals and an intermediate terminal arranged in a straight line' and permanently connected with said terminal base and having portions extending through the respective apertura in said casing and said insulating enclosure member to a point exterior of said casing and portions extending transversely across said hase, and a ilat iix'ed resistance element oi the same 40 size and shape as said terminal base iltting flatwise against said terminal base and engaging the portions of the terminals extending transversely across the terminal base.

2. A resistance unit including a rectangular 45 casing formed with a pair of foldable sides adapted to be folded over alter the unit has been assembled, a rectangular terminal base having a plurality oi' terminal members positioned at spaced points along the base, a nxed resistance 50 element of approximately the same sise and shape as said base ntting against said terminal base so as to contact with said terminals, and insulating means surrounding said terminal base and said resistance element, the folding sides o! 55 said casing when in operative position acting to hold the parts together so there will be a desired contact between the resistance element and said terminals to secure good electrical contact continually.. 60

3.111 aresistance unito! thecharacter described, a resistance element having a base and a wiring of resistance wire thereon extending from substantially one end of. the base to the other,aterminalunitcomprisinganatbaseoi65 insulating material adapted to nt ilatwise lainst the resistance element, and not less than three terminals carried by said base at spaced points along its length. said terminals iitting against certain wires of said resistance element, and 70 means for holding the resistance element in contact in said terminal unit.

4. A resistance unit comprising a casing having a plurality of openings in one face, an insuiating sheath iitting into said casing and pro- 75 a terminal unit comprising allai:

ing material, a pair.ot'end terminal and atleast one intermediate terminal member. saidterm'inal unit-ttingewithin said insulating sheathing and having the terminals extending through said apertures. each .ofsaid having a base iiange, and a plurality oi resistance .elements fitted ilatwise mt said terminal unit, the flange of one of the bridging the abutting ends of twov of the resistance elements, while the flanges of the engage the resistance element at the respective ends thereof. i

5. A resistance unit including a casing formed with a pair ot foldahle sides adapted to be folded over after the unit ha'sgbeenassembled. a ter-ini-` nal base, a terminal member zat each end o! said base, each of said members'having a part clinched to said terminal base. an int'e'imediate terminal memberhaving a part cunched to said terminal base intermediate the ends o! the terminal base. a resistance elementtted against said terminal base and contacting with 'said terminal members ofthe position of said intermediate terminal member, vvand. insulating means surrounding said base and said resistance element, the toldable sides, of said casing when in operative ltl'ng to hold the parts together so that there willbe a desired Qngagement between the resistance element and terminalmemhersto's'ecureeiectrical oon- 6.1i: unit defV elementhavingahaseand awirgolresistsneewireextendingirom sub- '5 stanliallyoneendstthehasetothecthenaterminal nexttoand in ement with said resistance element and from one end to the'other oi said said terminal unit eonxpri'isingfa4 base at insulat-xlo from the ends. a. pluralityaf-terminals. each ot said'terminals having-"upsia'ndingposts 'and a 'iiangedbase,oneofsaidterminalsextending said aperturewith the-flanged base nt- 15 thebase of terminal unit. theother terminais'heing arranged at the ends OI-.thehase of the terminal unit with the respectivenanged bases of said terminals iltting iiatwise Meinst one surface 'of 2o thebaseoitheterminalunitandalsoilatwise. against .certain wires oi' said resistance element all of said terminals having their Banged bases turned overthe respective edges o! said base of insulating material andl clinched. and means for 25 holding the resistance' unit in contact with the. terminal unit so that the circuit between lany twootsaid terminalawillbethroughpartofsaid resistance element.

` JOHN J. MUCHER. 30 

